Edexcel iGCSE Chemistry -1.51 Electrical Conductivity of Covalent Compounds- Study Notes- New Syllabus
Edexcel iGCSE Chemistry -1.51 Electrical Conductivity of Covalent Compounds- Study Notes- New syllabus
Edexcel iGCSE Chemistry -1.51 Electrical Conductivity of Covalent Compounds- Study Notes -Edexcel iGCSE Chemistry – per latest Syllabus.
Key Concepts:
1.51 know that covalent compounds do not usually conduct electricity
1.51 Electrical Conductivity of Covalent Compounds
Key Statement:
Covalent compounds do not usually conduct electricity.
Why Is This?
Electrical conductivity requires:
- Mobile charged particles (ions or electrons)
In covalent compounds:
- Electrons are shared in bonds.
- There are no free ions.
- There are no delocalised electrons (in most cases).
Therefore, there are no mobile charged particles to carry current.
Example: Water
\( \mathrm{H_2O} \)
Water is a covalent compound.
Pure water does not conduct electricity because it contains no free ions.
Important Exception
Graphite is a covalent substance but conducts electricity.
This is because it has delocalised electrons that can move.
| Type of Substance | Mobile Charged Particles? | Conducts Electricity? |
|---|---|---|
| Covalent compound | No | No |
| Graphite | Yes (delocalised electrons) | Yes |
| Ionic (molten/aqueous) | Yes (ions) | Yes |
GCSE Explanation Structure
- Covalent compounds consist of molecules.
- They have no free ions.
- Electrons are localised in bonds.
- Therefore, they cannot carry electrical charge.
Example 1 (Conceptual):
Why does methane not conduct electricity?
▶️ Answer/Explanation
\( \mathrm{CH_4} \) is a simple molecular compound.
It contains no free ions.
Electrons are held in covalent bonds.
There are no mobile charge carriers.
Example 2 (Comparison):
Explain why sodium chloride conducts electricity when molten but methane does not.
▶️ Answer/Explanation
Molten sodium chloride has free-moving ions.
Methane consists of neutral molecules.
There are no charged particles in methane.
Therefore, methane does not conduct.
Example 3 (Hard):
Explain fully why most covalent compounds do not conduct electricity, even when molten.
▶️ Answer/Explanation
Covalent compounds consist of neutral molecules.
They do not form ions when melted.
Electrons remain localised in covalent bonds.
There are no mobile charged particles.
Without mobile charge carriers, current cannot flow.